South Australian jockey Dylan Caboche has been suspended for two weeks for punching his mount She's Reneldasgirl in South Australia on Wednesday.
Caboche, who appeared to have difficulty getting the horse to settle, dismounted and punched the horse in the stomach before the field went into the gates at Port Lincoln.
The horse finished eighth in a field of 10 in a 1390-metre Maiden Plate.
Thoroughbred Racing South Australia condemned the incident in a statement on Wednesday evening.
"TRSA does not condone and will not tolerate such behaviour and it is hoped this penalty - which will remain on the rider's record and will impact his earning ability - will send a strong signal to others," it read.
Animal protection group, the Coalition for the Protection of Racehorses, also denounced Caboche's actions and called for him to expelled from the horse racing industry for life.
The group's spokesman, Ward Young, described his punishment as "grossly inadequate".
"You don't get to punch a horse and get away with it," Mr Young said.
"It's time for the racing industry to clean up their act, and they can start by expelling violent mugs like Caboche.
"If jockeys can't control their tempers, they don't deserve to be on the racetrack. If this is what we see on race day, we can only imagine what goes on behind the scenes.
"It looks like you can add punching horses to the list of cruelty in horse racing in addition to jumps racing, whipping horses, two-year-old racing, and sending them to the knackers."
Victorian apprentice Brandon Stockdale was fined $500 after punching his mount Maid To Measure in the stomach at Sandown in August. Stockdale said he was frustrated after wasting to make a ride later in the program and vowed that it wouldn't happen again.